A fiber optic cable assembly is a device that carries a light signal from one end to another. A typical fiber optic cable assembly includes a segment of fiber optic cable, a first fiber optic connector that connects to one end of the fiber optic cable segment, and a second fiber optic connector that connects to another end of the fiber optic cable segment. The fiber optic connectors of the fiber optic cable assembly typically connect with other fiber optic connectors or adaptors in a male/female configuration, or in a snap fit manner using sets of matching bumps and holes. Some fiber optic connectors further include alignment posts to ensure proper alignment of fiber ends.
Fiber optic cable assemblies are commonly used to connect data communications equipment.together, and are available in an assortment of standard lengths. For example, fiber optic cable assemblies having long lengths of fiber optic cable segments can be laid out to enable high-speed communications over extremely long distances, e.g., in a wide area network (WAN), in an oversees telephone network, etc. As another example, some fiber optic cable assemblies, which are typically not as long, can run along walls and ceilings of a building to connect computers together in a local area network (LAN). As yet another example, some fiber optic cable assemblies (called patch cords), which have relatively short fiber optic cable segments, can operate as jumper cables and plug into an exposed rack-mounted set of data communications devices called a patch panel in order to provide a centrally located set of connections in a switchboard-like manner. Such data communications devices typically have their own housings and provide sets of external ports into which a person (e.g., a network administrator) can manually plug the fiber optic connectors of the fiber optic cable assemblies. As such, the patch panel is typically located in a computer room or in a locked utility closet in order to prevent tampering and/or to protect against an unauthorized person inadvertently knocking a cable loose and re-plugging that cable into an incorrect port.
The fiber optic cable segments of some fiber optic cable assemblies have a thin single fiber, i.e., a single mode fiber, and are suited for carrying a single light signal. Others have a relatively larger single fiber, i.e., a multimode fiber, and are suited for concurrently carrying multiple light signals, each light signal having a slightly different reflection angle within the fiber. Some fiber optic cable segments have multiple fibers for carrying multiple light signals.
Some fiber optic cable assemblies have specially configured connectors or additional fittings (e.g., elbows or sheathings) that provide particular bend radii to the fiber optic cable segments over particular lengths (e.g., a 90 degree bend over a 1.5 inch span). Such connectors and fittings attempt to prevent the fiber optic cable segments from overbending, i.e., from being moved into a position that can result in excessive light energy loss and/or permanent disfiguration of the fiber.
Unfortunately, there are deficiencies to the above-described fiber optic connecting approaches. In particular, none of the above-described fiber optic connecting approaches are well-suited for connecting multiple electronic circuit boards together in a relatively small footprint (e.g., within a single electronic equipment cabinet) to enable the circuit boards to communicate with each other. Although patch cords are suitable for connecting rack-mounted patch panel data communications devices together, patch cords alone are not well-suited for connecting circuit boards together. For example, a typical circuit board can exchange over a hundred signals with an external device (e.g., typically through a backplane that carries electrical signals). This quantity of signals makes the job of manually connecting fiber optic cables between several circuit boards an arduous and almost impractical task. Additionally, the resulting set of installed cable assemblies, which can quickly look like an overwhelming tangled web of cables, would tend to block air flow around the circuit boards thus preventing the circuit boards from receiving adequate cooling. Furthermore, replacement of a circuit board would become an extremely time consuming and tedious endeavor since fiber optic cable assemblies would need to be accurately and delicately removed from the old circuit board and plugged into the new circuit board. Moreover, even if a person were to achieve plugging in fiber optic cable assemblies to tie all the circuit boards together, there is a lack of control over who can later access and change/move the fiber optic cable assemblies, which is handled today for patch panels by locating the patch panels in a computer room or closet with restricted access.
In contrast to the above-described conventional fiber optic connecting approaches, an embodiment of the invention is directed to techniques for connecting circuit boards together using an interconnect which includes two planar members and a set of fiber optic cable assemblies having fiber optic connectors which extend through holes in the planar members. Accordingly, the circuit boards can engage with the interconnect (and thus communicate with each other through the interconnect) in a manner that enables them to easily install onto and de-install from the interconnect (e.g., during replacement). Additionally, the fiber optic cable assemblies can be positioned relative to the planar members such that there is no interference with an air flow that cools the circuit boards, and no opportunity for tampering or inadvertently modifying the interconnect.
One arrangement of the invention is directed to an electronic system having a set of circuit boards and an interconnect. Each of the set of circuit boards includes a set of fiber optic circuit board connectors. The interconnect includes (i) a first planar member, (ii) a second planar member that is substantially parallel to the first planar member, and (iii) a set of fiber optic cable assemblies. Each fiber optic cable assembly includes a fiber optic cable segment, a first fiber optic interconnect connector which fastens to one end of that fiber optic cable segment and a second fiber optic interconnect connector which fastens to another end of that fiber optic cable segment. Each fiber optic interconnect connector extends through a hole defined by one of the first and second planar members. Furthermore, each fiber optic interconnect connector is configured to engage with a fiber optic circuit board connector. This arrangement provides a well-organized and controlled configuration of fiber optic pathways between circuit boards.
In one arrangement, each of the set of circuit boards further includes a section of circuit board material, a set of integrated circuits mounted to the section of circuit board material, and a set of fiber optic transceivers mounted to the section of circuit board material and coupled to the set of fiber optic circuit board connectors. The set of fiber optic transceivers are in electrical communication with the set of integrated circuits. Additionally, each fiber optic circuit board connector has (i) a base portion which is rigidly disposed relative to the section of circuit board material, (ii) a connecting portion which is capable of moving relative to the section of circuit board material, and (iii) a resilient portion disposed between the base portion and the connecting portion of that fiber optic circuit board connector.
In one arrangement, the fiber optic cable segment of each fiber optic cable assembly of the set of fiber optic cable assemblies has a same length. Accordingly, the fiber optic signals passing through the set of fiber optic cable assemblies are single mode signals, the signals will essentially have the same delays.
In one arrangement, the first and second fiber optic interconnect connectors of each fiber optic cable assembly have sides which taper toward each other in a trapezoidal manner. Preferably, interconnect connectors have tapering sides on all four sides rather than just two sides. Accordingly, the circuit board connectors self-align with their corresponding interconnect connectors.
In one arrangement, interconnect further includes a set of standoffs which position the first and second planar members such that the first and second planar members are substantially parallel to each other. The standoffs facilitate positioning of the planar members relative to each other, and prevent the planar members from moving too close to each other where they could otherwise squish and damage the fiber optic cable segments. In another arrangement, each fiber optic interconnect connector defines a connecting portion and a standoff portion such that the connecting portion of that fiber optic interconnect connector contacts one of the first and second planar members and the standoff portion of that fiber optic interconnect connector contacts the other of the first and second planar members.
In one arrangement, the interconnect further includes a vacuum injected medium disposed within an interconnect inner region defined by the first and second planar members. The vacuum injected medium holds the fiber optic cable segment and first and second fiber optic connectors of each fiber optic cable assembly of the set of fiber optic cable assemblies in place. Preferably, the vacuum injected medium prevents tampering or manipulating of the fiber optic cable assemblies.
In one arrangement, the interconnect further includes a set of electrical conductors which extend along at least one of the first and second planar members. Accordingly, the interconnect can be used for providing electrical signals (e.g., power supply signals, circuit board presence indicator signals, etc.) to the circuit boards in addition to fiber optic signals.
The features of the invention, as described above, may be employed in electronic systems, devices and procedures as well as other components such as those of EMC Corporation of Hopkinton, Mass.